Redis之实战篇（与Mybatis整合）
具体步骤如下：
1，准备好ssm工程，如果有不会的，可以参考
springmvc+mybatis整合
2，准备好Redis服务器
3，构建 pom.xml 文件，这个pom文件和之前ssm的基本一样，只是添加了redis的支持
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.demo</groupId>
<artifactId>demo</artifactId>
<packaging>war</packaging>
<version>0.0.1-SNAPSHOT</version>
<name>demo Maven Webapp</name>
<properties>
<!-- spring版本号 -->
<spring.version>4.2.2.RELEASE</spring.version>
<!-- mybatis版本号 -->
<mybatis.version>3.3.0</mybatis.version>
<!-- log4j日志文件管理包版本 -->
<slf4j.version>1.7.7</slf4j.version>
<log4j.version>1.2.17</log4j.version>
</properties>
<dependencies>
<dependency>
<groupId>jdk.tools</groupId>
<artifactId>jdk.tools</artifactId>
<version>1.7</version>
<scope>system</scope>
<systemPath>${JAVA_HOME}/lib/tools.jar</systemPath>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<!-- 表示开发的时候引入，发布的时候不会加载此包 -->
<scope>test</scope>
</dependency>
<!-- spring核心包 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-oxm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- mybatis核心包 -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<!-- mybatis/spring包 -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.2.2</version>
</dependency>
<!-- 导入java ee jar 包 -->
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>7.0</version>
</dependency>
<!-- 导入Mysql数据库链接jar包 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.30</version>
</dependency>
<!-- 导入dbcp的jar包，用来在applicationContext.xml中配置数据库 -->
<dependency>
<groupId>commons-dbcp</groupId>
<artifactId>commons-dbcp</artifactId>
<version>1.2.2</version>
</dependency>
<!-- JSTL标签类 -->
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!-- 日志文件管理包 -->
<!-- log start -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<!-- 格式化对象，方便输出日志 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.1.41</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
<!-- log end -->
<!-- 映入JSON -->
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.9.13</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.1.0</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.1.0</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.1.0</version>
</dependency>
<!-- 上传组件包 -->
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.1</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.4</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.9</version>
</dependency>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.8.0</version>
</dependency>
<dependency>
<groupId>commons-pool</groupId>
<artifactId>commons-pool</artifactId>
<version>1.6</version>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>${java-version}</source>
<target>${java-version}</target>
<encoding>utf8</encoding>
</configuration>
</plugin>
</plugins>
</build>
</project>
4，编写Redis需要用的2个工具类 RedisUtil.java和SerializeUtil.java。这个在前一篇已经有过，这里不再重复贴代码了。
5，新增一个Cache类，需要实现 org.apache.ibatis.cache.Cache 接口
package demo.cache;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.ibatis.cache.Cache;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import demo.utils.RedisUtil;
import demo.utils.SerializeUtil;
public class MybatisRedisCache implements Cache {
private static Logger logger = LoggerFactory.getLogger(MybatisRedisCache.class);
/** The ReadWriteLock. */
private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
private String id;
public MybatisRedisCache(final String id) {
if (id == null) {
throw new IllegalArgumentException("Cache instances require an ID");
}
logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>MybatisRedisCache:id="+id);
this.id = id;
}
public String getId() {
return this.id;
}
public void putObject(Object key, Object value) {
logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>putObject:"+key+"="+value);
RedisUtil.getJedis().set(SerializeUtil.serialize(key.toString()), SerializeUtil.serialize(value));
}
public Object getObject(Object key) {
Object value = SerializeUtil.unserialize(RedisUtil.getJedis().get(SerializeUtil.serialize(key.toString())));
logger.debug(">>>>>>>>>>>>>>>>>>>>>>>>getObject:"+key+"="+value);
return value;
}
public Object removeObject(Object key) {
return RedisUtil.getJedis().expire(SerializeUtil.serialize(key.toString()),0);
}
public void clear() {
RedisUtil.getJedis().flushDB();
}
public int getSize() {
return Integer.valueOf(RedisUtil.getJedis().dbSize().toString());
}
public ReadWriteLock getReadWriteLock() {
return readWriteLock;
}
}
6，开启mybatis对缓存的支持，在本项目中，是修改 spring-mybatis.xml 文件
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <!-- 自动扫描mapping.xml文件 --> <property name="mapperLocations" value="classpath:demo/mapping/*.xml"></property> <property name="configurationProperties"> <props> <prop key="cacheEnabled">true</prop> <prop key="lazyLoadingEnabled">false</prop> <prop key="aggressiveLazyLoading">true</prop> </props> </property> </bean>
其中：
<prop key="cacheEnabled">true</prop>
是开启的关键。
7，在相关的 mapper.xml 添加所需要用的缓存类，我们这里是在 TUserMapper.xml 中添加
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="demo.dao.TUserMapper">
<cache type="demo.cache.MybatisRedisCache" />
<resultMap id="BaseResultMap" type="demo.domain.TUser">
<id column="id" property="id" jdbcType="INTEGER" />
<result column="username" property="username" jdbcType="VARCHAR" />
<result column="password" property="password" jdbcType="VARCHAR" />
<result column="createtime" property="createtime" jdbcType="TIMESTAMP" />
</resultMap>
<sql id="Base_Column_List">
id, username, password, createtime
</sql>
<select id="selectByPrimaryKey" resultMap="BaseResultMap"
parameterType="java.lang.Integer">
select <include refid="Base_Column_List" /> from t_user where id = #{id,jdbcType=INTEGER}
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
delete from t_user
where id = #{id,jdbcType=INTEGER}
</delete>
<insert id="insert" parameterType="demo.domain.TUser">
insert into t_user (id, username, password,
createtime)
values (#{id,jdbcType=INTEGER}, #{username,jdbcType=VARCHAR},
#{password,jdbcType=VARCHAR},
#{createtime,jdbcType=TIMESTAMP})
</insert>
<insert id="insertSelective" parameterType="demo.domain.TUser">
insert into t_user
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="id != null">
id,
</if>
<if test="username != null">
username,
</if>
<if test="password != null">
password,
</if>
<if test="createtime != null">
createtime,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="id != null">
#{id,jdbcType=INTEGER},
</if>
<if test="username != null">
#{username,jdbcType=VARCHAR},
</if>
<if test="password != null">
#{password,jdbcType=VARCHAR},
</if>
<if test="createtime != null">
#{createtime,jdbcType=TIMESTAMP},
</if>
</trim>
</insert>
<update id="updateByPrimaryKeySelective" parameterType="demo.domain.TUser">
update t_user
<set>
<if test="username != null">
username = #{username,jdbcType=VARCHAR},
</if>
<if test="password != null">
password = #{password,jdbcType=VARCHAR},
</if>
<if test="createtime != null">
createtime = #{createtime,jdbcType=TIMESTAMP},
</if>
</set>
where id = #{id,jdbcType=INTEGER}
</update>
<update id="updateByPrimaryKey" parameterType="demo.domain.TUser">
update t_user
set username = #{username,jdbcType=VARCHAR},
password = #{password,jdbcType=VARCHAR},
createtime = #{createtime,jdbcType=TIMESTAMP}
where id = #{id,jdbcType=INTEGER}
</update>
<select id="selectAll" resultMap="BaseResultMap">
select <include refid="Base_Column_List" /> from t_user
</select>
</mapper>
其中：
<cache type="demo.cache.MybatisRedisCache" />
是关键。
然后就可以在自己写的测试类或者controller中做测试了，测试的时候可以把日志级别设置为debug级别，这样可以看到Mybatis的sql语句。当走缓存的时候，是不会打印sql语句的，反之会出现sql语句。
例如，我们在原有的数据里，新加了一条数据，这时缓存数据和数据库数据就对应不上，可以看到日志里有sql语句打印
[org.mybatis.spring.SqlSessionUtils] - Creating a new SqlSession [org.mybatis.spring.SqlSessionUtils] - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@1005765] was not registered for synchronization because synchronization is not active [demo.cache.MybatisRedisCache] - >>>>>>>>>>>>>>>>>>>>>>>>getObject:-1445659396:380449231:demo.dao.TUserMapper.selectAll:0:2147483647:select id, username, password, createtime from t_user:SqlSessionFactoryBean=null [demo.dao.TUserMapper] - Cache Hit Ratio [demo.dao.TUserMapper]: 0.0 [org.springframework.jdbc.datasource.DataSourceUtils] - Fetching JDBC Connection from DataSource [org.mybatis.spring.transaction.SpringManagedTransaction] - JDBC Connection [jdbc:mysql://127.0.0.1:3306/demo, UserName=root@localhost, MySQL Connector Java] will not be managed by Spring [demo.dao.TUserMapper.selectAll] - ==> Preparing: select id, username, password, createtime from t_user [demo.dao.TUserMapper.selectAll] - ==> Parameters: [demo.dao.TUserMapper.selectAll] - <== Total: 9 [demo.cache.MybatisRedisCache] - >>>>>>>>>>>>>>>>>>>>>>>>putObject:-1445659396:380449231:demo.dao.TUserMapper.selectAll:0:2147483647:select id, username, password, createtime from t_user:SqlSessionFactoryBean=[demo.domain.TUser@4f6d47, demo.domain.TUser@8f7ea3, demo.domain.TUser@c309e0, demo.domain.TUser@bd7ea6, demo.domain.TUser@c5fc10, demo.domain.TUser@2784fd, demo.domain.TUser@8c0b75, demo.domain.TUser@443aea, demo.domain.TUser@177e204]
一旦这个执行过一次后，再执行（不再有数据变更），可以看到，也就不再有sql语句的打印了。
[org.mybatis.spring.SqlSessionUtils] - Creating a new SqlSession [org.mybatis.spring.SqlSessionUtils] - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@b14a45] was not registered for synchronization because synchronization is not active [demo.cache.MybatisRedisCache] - >>>>>>>>>>>>>>>>>>>>>>>>getObject:-1445659396:380449231:demo.dao.TUserMapper.selectAll:0:2147483647:select id, username, password, createtime from t_user:SqlSessionFactoryBean=[demo.domain.TUser@78471b, demo.domain.TUser@847332, demo.domain.TUser@1a6f080, demo.domain.TUser@f78840, demo.domain.TUser@11232a8, demo.domain.TUser@1bbe24e, demo.domain.TUser@672d9, demo.domain.TUser@15e2565, demo.domain.TUser@1e93ee7] [demo.dao.TUserMapper] - Cache Hit Ratio [demo.dao.TUserMapper]: 0.6666666666666666 [org.mybatis.spring.SqlSessionUtils] - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@b14a45] [demo.domain.TUser@78471b, demo.domain.TUser@847332, demo.domain.TUser@1a6f080, demo.domain.TUser@f78840, demo.domain.TUser@11232a8, demo.domain.TUser@1bbe24e, demo.domain.TUser@672d9, demo.domain.TUser@15e2565, demo.domain.TUser@1e93ee7]
备注：在网上看到有些人说mybatis和redis整合的时候，数据库使用mysql总是加载第一页的数据，不会显示以后的数据，经测试，可以正确加载指定页数的数据，分页也是采用常规的分页方法，这里就不再做描述了。